%documentstyle{article}                       % without NFSS
\documentclass{article}                       % with    NFSS
 \textheight15cm \textwidth11cm \parindent0mm \parskip 1ex plus2ex minus0.8ex
\begin{document}
default type                                                        \par \medskip
The following line acts differently with or without NFSS!           \par
{\bf These {\rm are \bf four} words.}                               \par\bigskip
{\tiny tiny}                              \par
{\scriptsize scriptsize}                  \par
{\footnotesize footnotesize}              \par
{\small small}                            \par
{\normalsize normalsize}                  \par
{\large large}                            \par
{\Large Large}                            \par 
{\LARGE LARGE}                            \par
{\huge huge}                              \par
{\Huge Huge} 
\end{document}
